Internal combustion engine provided with an accumulator injection system

ABSTRACT

An internal combustion engine includes an injection system that is configured as a high-pressure accumulator system in which the number of parts is small and the injection system can be easily assembled. The connecting fittings for the connection of the high-pressure lines are laterally offset with respect to the appertaining injection valves and in that the absolute magnitude of said offset is identical for all injection valves of a row of cylinders of the internal combustion engine.

The present invention relates to an internal combustion engine with aninjection system that is configured as a high-pressure accumulatorsystem, whereby at least one high-pressure pump is connected via ahigh-pressure supply line to a tubular high-pressure accumulator havingconnection fittings to which high-pressure lines are connected thatestablish valve-controlled flow connections to injection valves that areused in the cylinder head of the internal combustion engine and thatprotrude into working areas formed by the cylinders, the pistons and thecylinder head.

BACKGROUND

Such an internal combustion engine is known from German patentapplication DE 199 365 34 A1. This internal combustion engine has atubular high-pressure accumulator that is attached to the internalcombustion engine. The special feature of this tubular high-pressureaccumulator is that a continuous connection strip is shaped onto thehigh-pressure accumulator or else there are connection fittings shapedon that are configured with such a width that the bores for connectingthe high-pressure lines can be positioned at different places of theconnection fittings. As a result, it should be possible to use ahigh-pressure accumulator part for similar internal combustion engines.

SUMMARY OF THE INVENTION

An object of the present invention is to provide an internal combustionengine having a high-pressure accumulator system with a small number ofparts so as to facilitate the assembly of the injection system.

The present invention provides an internal combustion engine with aninjection system that is configured as a high-pressure accumulatorsystem, whereby at least one high-pressure pump is connected via ahigh-pressure supply line to a tubular high-pressure accumulator havingconnection fittings to which high-pressure lines are connected thatserve to establish valve-controlled flow connections to injection valvesthat are used in the cylinder head of the internal combustion engine andthat protrude into working areas formed by the cylinders, the pistonsand the cylinder head. The connection fittings are arranged laterallyoffset with respect to the appertaining injection valves and in that theabsolute magnitude of the offset is the same for all of the injectionvalves of one cylinder row of the internal combustion engine. Thelateral offset of the connection fittings relative to the appertaininginjection valves—which are each fitted with an electrically operatedcontrol block and which are preferably arranged in the middle of theappertaining cylinders in the preferably shared cylinder head of thecylinders of one cylinder row—allows the parts of the injection systemto be assembled without any problem since, for instance, the injectionvalves with their high-pressure connections—which optionally exitlaterally from the cylinder head—and the tubular high-pressureaccumulator are assembled first and afterwards the correspondinghigh-pressure lines can subsequently be placed between the injectionvalves or between the high-pressure line connections and thehigh-pressure accumulator system without any problem due to the lateraloffset of the connections. In this context, it should be taken intoconsideration that the high-pressure accumulator system is arranged inclose proximity to the injection valves in order to keep the length ofthe high-pressure lines short so as to create a hydraulically stiffinjection system. As a result of the fact that the absolute magnitude ofthe offset is the same for all of the cylinders of one cylinder row andespecially matches the distance of the injection valves in the cylinderhead, the injection lines can be configured at least all with the samelength. This is advantageous for adjusting the injection system.

In an embodiment of the invention, the offset of at least one cylinderat the end is arranged differently from the orientation of the offset ofthe other cylinders. This configuration ensures that the high-pressureaccumulator system has a compact design and, in particular, that it doesnot extend beyond one cylinder row.

In another embodiment of the invention, there are two differently shapedhigh-pressure lines for the cylinder row of the internal combustionengine. This is the case when the injection valves are provided with alateral high-pressure line connection and this connection is pivoted byan angle relative to the transverse axis of the cylinder head. If thehigh-pressure line connection is oriented precisely crosswise to thelongitudinal axis of the cylinder head, all of the high-pressure linescan be shaped the same in an alternative embodiment.

In another embodiment of the invention, the at least one high-pressurepump is arranged close to the cylinder head in a housing, preferably thecrankcase of the internal combustion engine, and it is actuated by aninjection pump cam that is arranged on the gas-exchange camshaft of theinternal combustion engine. This arrangement, in turn, allows a verycompact structure of the internal combustion engine and, in particular,does not require any additional drive devices for the high-pressurepump.

In a refinement of the invention, two high-pressure pumps that lie nextto each other at a distance are associated with adjacent cylinders. Thismakes it possible to utilize compact, inexpensive high-pressure pumps.Moreover, the use of two high-pressure pumps brings about anequalization of the pressure build-up in the high-pressure accumulator.

In another embodiment, the high-pressure supply lines that connect thehigh-pressure pumps to the high-pressure accumulator are configuredidentically to each other. This minimizes the requirements in terms ofparts here as well.

BRIEF DESCRIPTION OF THE DRAWING

In a refinement of the invention, a control block for controlling orregulating the fuel pressure to be established in the high-pressureaccumulator is arranged on the inlet side of the at least onehigh-pressure pump. Here, the control block is arranged next to the onehigh-pressure pump or between the two high-pressure pumps. As analternative, the control block can be integrated into the support frameof the fuel filter. This embodiment translates into a very compactinjection device.

Additional advantageous embodiments can be gleaned from the descriptionof the drawing in which an embodiment of the invention shown in theFIGURE is described in greater detail.

DETAILED DESCRIPTION

A gear-driven fuel delivery pump 1 conveys fuel from a fuel tank (notshown here) via a feed line 2 into the support frame 3 of a fuel filter4 in the form of a cup. After the fuel flows through the fuel filter 4,it is introduced into a control block 6 via a flow line 5. The controlblock 6 contains a pressure-control valve and a zero-delivery throttlethat is constantly discharging a small amount of fuel, whereby thisamount of fuel discharged by the pressure-control valve and by thezero-delivery throttle is discharged into a return line 9. Thepressure-control valve determines the amount of fuel to be fed to twohigh-pressure pumps 7 a, 7 b via a feed line 8. Fuel that is to bedischarged is returned to the support frame 3 of the fuel filter 4 viathe return line 9. The high-pressure pumps 7 a, 7 b are connected to atubular high-pressure accumulator 11 via identically configuredhigh-pressure supply lines 10 a, 10 b. Furthermore, there are connectionfittings 12 a, 12 b, 12 c, 12 d, 12 e, 12 f on the high-pressureaccumulator 11 to which high-pressure lines 13 a, 13 b, 13 c, 13 d, 13e, 13 f are fastened which are not connected to injection valves orhigh-pressure connections. (In the case of the high-pressure line 13 alocated on one end across from the connection on the connection fitting12 a, a ring-shaped opening is shown that is formed in the cylinder headand that accommodates a high-pressure connection). The high-pressureaccumulator 11 is fastened to the internal combustion engine by means offasteners 14 a, 14 b, 14 c, particularly to the cylinder head. Thehigh-pressure accumulator 11 has a connection for a pressure sensor 15and, on the opposite side, a connection for a discharge line 16 that isconnected to the return line 9. A pressure-limiting valve 17 is locatedupstream from the discharge line 16.

The high-pressure pumps 7 a, 7 b are installed directly in the crankcaseof the internal combustion engine and they have roller tappets 18 thatroll on injection pump cams that are arranged on the camshaft of theinternal combustion engine between the gas-exchange cams of a cylinderunit. Here, the gas-exchange cams, the injection pump cam and thebearing areas of a cylinder unit following the gas-exchange cams form acontinuous unit without interruptions. These high-pressure pumps 7 a, 7b each have a plunger that is actuated by one of the roller tappets 18and that is designed without a control edge so that it always conveys aprescribed amount of fuel as long as the feed is sufficient. Asmentioned above, the fuel pressure in the high-pressure accumulator 11is controlled or regulated by the pressure-control valve of the controlblock 6 in that the amount of fuel fed to the high-pressure pumps 7 a, 7b is controlled. In the embodiment shown, the control block 6 ispositioned between the high-pressure pumps 7 a, 7 b. In an alternativeembodiment, this control block 6 can also be integrated into the supportframe 3 of the fuel filter 4.

1. An internal combustion engine that includes an injection systemconfigured as a high-pressure accumulator system, the internalcombustion engine comprising: at least one high-pressure pump; a tubularhigh-pressure accumulator having a plurality of connection fittings; ahigh-pressure supply line connecting the at least one high-pressure pumpto the tubular high-pressure accumulator; and a plurality ofhigh-pressure connection lines each connected to one of the connectionfittings and configured to provide a valve-controlled flow connection toa respective one of a plurality of injection valves of a cylinder row ofthe internal combustion engine, wherein each of the plurality ofconnection fittings is disposed laterally offset relative to thecorresponding injection valve, and wherein an absolute magnitude of theoffset is the same for each of the injection valves; wherein theplurality of high-pressure connection lines have two different shapes,and each high-pressure connection line has one of the two differentshapes.